Governments should develop and run opensource systems. That way different governments can collaborate to build better systems through open innovation. Not wasting tax payers money on closed source. I bet tax and pension systems have the same basic requirements cross countries with some local specifics.
opensource system can create much needed transparency in government project and organization effort. In my home country the unemployment agency spent atrocious amount of money to create an unusable job-posting app; something private companies do for fraction of the cost. More surprisingly, they doubled down on it; instead of scrapping it when it wasn't delivering. My guess it that some nepotism/favoritism was at play, and if the project was at least open source it could've been examined by others.